The present invention relates to a scroll type fluid machine which is preferably employed in a compressor of a fluid, for example, an air or the like, a vacuum pump, an expansion machine and the like.
Generally, as a scroll fluid machine, there are a compressor compressing a fluid such as an air, a refrigerant or the like, a vacuum pump depressurizing an internal side of a container, an expander expanding the fluid and the like. This kind of scroll type fluid machine is provided with a fixed scroll which is fixed to a casing and is provided in a rising manner with a spiral wrap portion in a surface of a end plate, a orbiting scroll which is provided in a rising manner with a spiral wrap portion in a surface of a end plate and defines a plurality of fluid chambers compressing and expanding a fluid with respect to the fixed scroll on the basis of a orbiting motion, a drive shaft which is rotatably provided in the casing for orbiting the orbiting scroll, and a self-rotation preventing mechanism which prevents a self-rotation of the orbiting scroll and is constructed, for example, by an auxiliary crank mechanism. Further, the drive shaft has a crank pin serving as an eccentric shaft portion which is eccentric from a main shaft portion in a leading end side thereof, and is rotatably attached to the casing via a main bearing.
Further, the scroll type fluid machine drives the orbiting scroll via the drive shaft by a driving source such as a motor or the like. Accordingly, the scroll type fluid machine sequentially compresses a fluid, for example, the air, the refrigerant or the like within each of fluid chambers.
Further, as the scroll type fluid machine, there has been known a structure in which an annular elastic member is provided between a main bearing and a drive shaft, for enabling a load acting on a crank pin and a wrap at a time of an abnormal load to avoiding in all the radial directions (refer, for example, to JP-A-3-141883).